`akbasic_sink_init_tee()` wired write, writeln, readline, clear and --
conditionally -- moveto, and never `window`. The standalone AKGL frontend runs
the interpreter against a tee, so the fully implemented `sink_window()`
underneath it was unreachable: `WINDOW 0, 0, 20, 4` answered "WINDOW needs a
text device with a character grid, and this one has none" on the one build that
has a character grid. It reads as an oversight rather than a decision, because
`moveto` directly above it is forwarded with reasoning that applies unchanged.
`tee_window()` is that function, modelled on `tee_moveto()`, offered only when a
half can take it so the refusal still reads correctly through a stdio-only pair.
**Writing the test found a second one.** Both optional entry points are assigned
conditionally, and neither initializer cleared them first -- so a caller with a
sink on the stack got whatever was in that memory, and `CHAR` and `WINDOW`
decide whether they can act by testing those pointers for NULL. Both
`akbasic_sink_init_tee()` and `akbasic_sink_init_stdio()` now clear them. An
initializer that leaves a field alone is not an initializer.
tests/sink_tee.c gains a stand-in sink with a grid -- the two stdio halves have
neither entry point, which is exactly why they could not show that either is
forwarded -- and asserts both directions, the arguments arriving intact, and
that a grid-less pair still offers neither.
Verified end to end: `WINDOW 0, 0, 20, 4` then `PRINT` succeeds under
build-akgl/basic and still refuses by name under build/basic.
What this does *not* fix is that a drawing still has to be re-issued every
frame: the frontend never clears and SDL is double-buffered, so a drawing issued
once appears in one buffer only. Shrinking the text area makes the rest of the
window the program's; keeping something there is still the program's job. That
half is documented rather than fixed, and is filed as TODO.md section 9 item 5.
TODO.md section 6 item 31, struck.
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Reproduces deps/basicinterpret in C, in the idiom of the ak* libraries. All 41
.bas files in the reference's corpus produce byte-identical stdout, including
the trailing double newline on an error line -- that comes from basicError
building a string ending in \n and handing it to Println, and
array_outofbounds.txt encodes it.
The corpus is driven in place from the submodule as 41 individual CTest cases
rather than copied, so it cannot drift from upstream. Eighteen unit tests cover
what the corpus cannot reach.
Three structural changes carry most of the work. Go's three reflection lookups
(Command*, Function*, ParseCommand*) become one sorted dispatch table in
src/verbs.c searched with bsearch; adding a verb is a row and two functions. The
five Go maps become one fixed open-addressed table over aksl_strhash_djb2. And
run(), which owned the process until MODE_QUIT, splits into step() plus a
bounded run() -- goal 3 requires a host game to be able to bound execution, and
nothing in the library now terminates the process or touches SDL.
Output goes through an akbasic_TextSink vtable. src/sink_stdio.c is what makes
the corpus runnable with no SDL present; the akgl-backed sink is still to come
and is blocked on libakgl having no text-measurement call.
src/convert.c exists because libakstdlib's aksl_ato* family cannot report a
conversion failure (its TODO.md 2.1.5). The reference checks strconv's error at
four sites and turns it into a BASIC error; routing those through aksl_atoi
would have turned four diagnosable errors into wrong answers, with VAL("garbage")
quietly returning 0. TODO.md 1.9 records which libakstdlib calls are cleared for
use here and which are not.
Reference defects are reproduced, not fixed: the golden files encode the observed
behaviour and a silent correction is a behaviour change. TODO.md section 6 lists
sixteen, and tests/known_reference_defects.c asserts the *correct* contract for
six of them under AKBASIC_KNOWN_FAILING_TESTS, so a fix shows up as
"unexpectedly passed". Five of the sixteen were found by this port and are new:
subtraction stops after one operator so 1-2-3 computes 1-2 and abandons the rest
of the line (a wrong answer, not a refused one); a unary-minus argument inflates
a function's arity so ABS(-9) is rejected; a comparison operator in a line's
final column is dropped; hex literals never survive the scanner; and the
"Reserved word in variable name" check is dead code.
Where the reference reaches undefined behaviour by a route that is defined in Go
-- an out-of-range shift, a negative string multiplier, integer division by zero
-- this raises instead of inheriting the UB. No golden case exercises any of
them.
The top-level CMakeLists shadows add_test, set_tests_properties and
add_custom_target around all three add_subdirectory calls. Without it libakerror's
tests land in our suite as Not Run, and its un-namespaced `coverage` target stops
a coverage build from configuring at all. Test targets are akbasic_test_<name>:
bare test_<name> collides with libakstdlib's, which is what broke libakgl's
configure in c2b16d3.
ctest 59/59; ASan+UBSan 59/59; 92.3% line and 96.9% function coverage; no
warnings under -Wall -Wextra. Branch coverage is not a target, for the reason
libakstdlib and libakgl both record: the akerror macros expand into large branch
trees at every call site.
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
